You should alread be playing, played Half-Life and it's expensions.

Half-Life
Half-Life Opposing Force
Half-Life Blue Shift

These are the basic elements to get your attent to detail in half-life games.

In this mod, you need to recover backup the data of the most developed computer of Black Mesa.
So, you're on your way to backup Gibson's data.
There are some tricky puzzles, and Hard to find vents to proceed further. So look up for vents.

https://www.moddb.com/mods/half-life-the-world-machine

This is one of the classics.
The most I know that, you're a janitor, maybe for hazardous materials so you wear hev suit for the job.
Testing goes wrong and you're mission is to escape.

https://www.moddb.com/mods/caseclosed/downloads

An action takes place in black mesa. You wear HEV suit, and need to escape.

https://www.moddb.com/mods/davsub

You wake up in a hospital place and try to get out. Pretty classic and old mod.

https://www.moddb.com/mods/awaken/downloads

You're a white hev wearing scientist, and calls for signal help from black mesa, but signal not only goes to black mesa, but also some hecu looking group that is again tries to eliminate everyone in an arctic base.
This mod has custom and unique stuff, but kinda short like 40 mins or an hour.

https://www.moddb.com/mods/arctic-incident/downloads/ai-release

One of the best classic in half life modding history.

This mod is mostly about finding keycards and opening doors. It also has some surprises as play through.

Install part 1:
https://www.moddb.com/mods/lifes-end2/downloads/lifes-end1
Install part 2 over its files:
https://www.moddb.com/mods/lifes-end2/downloads/lifes-end-steam-fix2
Install part 3 over its files:
https://www.moddb.com/mods/lifes-end2/downloads/lifes-end-2023-fix
Install Better menu for mod:
https://www.moddb.com/mods/lifes-end2/addons/hl25-compatible-main-menu-and-hud

In this mod you're in black mesa and with no hev suit but working with blue shift armors to escape.
The mod is a bit dark, so try to level up your gamma in video/graphics settings.

Base full mod (hd models based):
https://www.moddb.com/mods/half-life-echoes/downloads/half-life-echoes-v14

Addon (ld gearbox models) [put them onto eachother or view and choose what model to use by using model viewer):
https://www.moddb.com/mods/half-life-echoes/addons/low-definition-pack-fix-personal-preferences
https://www.moddb.com/mods/half-life-echoes/addons/echoes-ld-2021-fix-pack
https://www.moddb.com/mods/half-life-echoes/addons/my-ld-echoes-pack

Want to arrive Black mesa before Adrian Shepherd?
So this is a way to play as Stefan and get the job done. This is the best op4 mod ever made. Gives more op4 experience and more.

Base mod link (mostly ld but some hd left over models):
https://www.moddb.com/mods/field-intensity/downloads/field-intensity-1-6

More ld models fix (view them with model viewer) (gina collete, adrian models ld here only):
https://www.moddb.com/mods/field-intensity/addons/fanmade-patch-jordons-ld-field-intensity-pack

More ld models fix 2nd:
https://www.moddb.com/mods/field-intensity/addons/npcs-revitalization-project-for-field-intensity

One of the best half life mods. And it has its own steam store page now.

https://cs2bus.com/steamstore/app/1707900/Delta_Particles/

You're in nation city which probably new york. Government established secret research bas "poke" has been taking xen species from xen or something like that.
After black mesa incident which is resonance cascade, poke tries to stop aliens but not really.


Both Poke646 and Pok646: Vendetta in one box, Anniversary edition download link:
https://www.moddb.com/mods/poke646-anniversary-edition

First version download link:
https://www.moddb.com/mods/poke646

Vendetta Sequel first version download link:
https://www.moddb.com/mods/poke646-vendetta

Check out best mods for Half-Life 2.

https://cs2bus.com/sharedfiles/filedetails/?id=3366769446